We demonstrate cyclic strain hardening and frequency-dependent fatigue life in electrodeposited nanocrystalline Ni subjected to tension–tension cyclic deformation. These observations are rationalized through mechanistic arguments based on the exhaustion of dislocation sources in the early stages of cyclic loading and on the domination of diffusive processes during later stages. 2005 Acta Materi...

Low strain hardening has hitherto been considered an intrinsic behavior for most nanocrystalline (NC) metals, due to their perceived inability to accumulate dislocations. In this Letter, we show strong strain hardening in NC nickel with a grain size of approximately 20 nm under large plastic strains. Contrary to common belief, we have observed significant dislocation accumulation in the grain i...

Sheet specimens of aluminum alloy 5754 were deformed along a series of bi-linear, equal-biaxial and uniaxial, strain paths while simultaneously measuring stress–strain behavior. The Visco-Plastic Self-Consistent crystal plasticity model, which incorporates texture evolution, was used to simulate the flow stress and hardening behavior based in part on the measured crystallographic texture before...

This paper presents a method for implicit stress integration of the Drucker–Prager material model with kinematic hardening. The stress integration of the material model is conducted using the incremental plasticity method, while the kinematic hardening of material is defined using nonlinear Armstrong–Frederick hardening. This type of granular material hardening occurs as a consequence of the cy...

In this paper we propose a modification of the polycrystalline shape memory alloy constitutive model originally proposed by Souza. By introducing a transformation strain energy with two different hardening coefficients, we are able to take into account the effect of the martensitic transformation of unfavorably oriented grains occurring after the main plateau. By choosing a proper second harden...

Mammalian appendages such as hair, quill and wool have a unique structure composed of a cuticle, a cortex and a medulla. The cortex, responsible for the mechanical properties of the fibers, is an assemblage of spindle-shaped keratinized cells bound together by a lipid/protein sandwich called the cell membrane complex. Each cell is itself an assembly of macrofibrils around 300 nm in diameter tha...

Plastic deformation of ARMCO iron processed by ECAP up to a maximum equivalent strain of sixteen (i.e., 1, 4, 8, and 16 ECAP passes) following route Bc was investigated by analyzing its microstructure and the stress-strain curves obtained after tensile tests at different levels of deformation. Three values of deformation (two in the plastic region taking into account the modified Crussard-Jaoul...